1. Field of the Invention
The invention relates to organic semiconductors contain benzodipyrrolidone unit. More particularly, to the synthesis of benzodipyrrolidone and their polymers and small molecules for electronic and optoelectronic applications.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by one or more reference numbers within brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
Conjugated semiconductors have received more and more attention due to their intriguing electronic and optoelectronic properties for application in a variety of optoelectronic devices, such as light-emitting diodes (LEDs)[1], organic thin film transistors (OTFTs)[2], and organic photovoltaics (OPVs)[3]. Such applications, inter alia, encourage the incessant exploration of conjugated semiconductors with new structures. In recent years, several organic colorants with specialized behavior in properties such as fluorescence, photoconduction, broad range absorption, and reversible redox, have been employed in organic electronics. One of the most successfully applied pigments is diketopyrrolopyrrole (DPP) with the underlying pyrolo[3,4-c]pyrrole-1,4-dione chromophoric system[4]. DPP has a planar, highly conjugated, lactam structure, resulting in strong π-π interactions and electron-withdrawing effects. During the last decade, it was shown that incorporation of DPP in polymers, oligomers and dendrimers resulted in emerging materials for optoelectronic applications, especially in organic thin film transistors (OTFTs)[5-9] and organic photovoltaic (OPVs). [10-13]
3,7-diphenyl-2,6-dioxo-1,2,5,6-tetrahydrobenzo[1,2-b:4,5-b′]dipyrrole (diphenylbenzodipyrrolidone) is a type of molecule originally prepared as a colorant and is similar in structure to DPP, but has the additional twist of being a quinodimethane derivative. Diphenylbenzodipyrrolidone can also be envisioned as a “stretched” DPP. Greenhalgh, C. W. et al, (Dyes and Pigments 1980, 1, 103-120) described the preparation of N,N′-dimethyl-3,7-diphenyl-2,6-dioxo-1,2,5,6-tetrahydrobenzo[1,2-b:4,5-b′]dipyrrole by condensation of N,N′-dimethyl-1,4-phenylenediamine with mandelic acid. Cui, W. B. et al, (Macromolecules 2011, 44, 7869-7873) described a modified method to make N,N′-dialkyl-3,7-diphenyl-2,6-dioxo-1,2,5,6-tetrahydrobenzo[1,2-b:4,5-b′]dipyrrole and make benzene and thiophene copolymers with N, N′-dioctyldodecyl-3,7-diphenyl-2,6-dioxo-1,2,5,6-tetrahydrobenzo[1,2-b:4,5-b′]dipyrrole. The polymers were applied to organic thin film transistors. However, only diphenylbenzodipyrrolidone and its derivatives were successfully synthesized by the above procedure. Attempts to synthesize diarylbenzodipyrrolidone with aryl as non-phenyl aromatics or dihalobenzodipyrrolidones were all failed.